I'll throw in my .02 as well.
- Messages: 10
- Calendar: 7 (I use fantastical because I like to color code different calendars and have them appear in month view)
- Photos: 10
- Camera: 8
- Weather: 10
- Clock: 10
- Maps: 6
- Videos: 10
- Wallet: 5
- Notes: 8
- Reminders: 10 (very useful to me)
- Stocks: (never use)
- iTunes Store: 1
- App Store: 8
- iBooks: 7
- News: (never use)
- Health: 6 (convoluted, like the music app)
- Settings: 6
- Phone: 10
- Safari: 8
- Mail: 9
- Music: 0 (what was once a nice intuitive app is now a marvel of bad engineering. I purchased a separate MP3 app for $5.99 just to easily play my songs)
- Activity: 7
- Watch: 10
- Facetime: 10
- Calculator: 10
- Game Center: 5
- Compass: 10 (especially like the leveling feature)
- Tips: 3
- Voice Memos: (never use)
- Contacts: 5
- Find my Friends: 4
- Find my iPhone: 10
- iCloud Drive: 6